Former Porsche R&D chief Wolfgang Hatz who stepped down in the wake of the diesel scandal afflicting the Volkswagen Group has been arrested in Germany as part of an investigation into the scandal by local prosecutors, a person familiar with the matter told Reuters on Thursday.

German business daily Handelsblatt first reported the arrest and Sueddeutsche Zeitung was first to disclose Hatz’s identity.

German prosecutors are only willing to state that someone was arrested on Thursday as part of an investigation into Audi. Prior to becoming Porsche’s R&D chief, Hatz headed powertrain development at Audi and Volkswagen.

If accurate, Hatz will be the first current or former board member of a VW Group brand to have been arrested. He will also be the fourth person in connection with the scandal behind bars. The others include former Audi manager Zaccheo Giovanni Pamio who was arrested in Germany in July, as well as James Liang and Oliver Schmidt who were arrested in the United States in 2016.

Pamio is still involved with a German investigation but may also end up facing charges in the U.S. since he doesn’t have extradition protection in Germany due to his Italian citizenship. Liang was sentenced to a 40-month prison term in August while Schmidt faces sentencing in December.

Five other former VW executives have been charged in the U.S.—Heinz-Jakob Neusser, Jens Hadler, Richard Dorenkamp, Bernd Gottweis, and Jürgen Peter—though all are in Germany and may not be extradited due to their German citizenship.